Protective cover for x-ray tubes



March 2l, 1933. A UNGELENK .Er AL, 1,902,474

n PROTECTIVE COVER FOR X-RAY TUBES Filed April l1, 1930 Inventors: Alfred Ungvelenk, f Walter` l-iowcmann, '29 MQW/gd TheLrvAttohn/eg,

Patented Mar. 21, 1933 ALFRED UNGELENK AND WALTER RCEMANN, E THURINGIA,

'ro GENERAL ELECTRIC COMPANY,

PROTECTIVE COVER Application led April 11, 1930, Serial No.

The present invention relates to X-ray apparatus, more particularly to the tube covering which serves as a protection against X-rays.

Notwithstanding the fact that the anode of an X-ray tube is designed to constrain the rays to a predetermined direction, there are usually present stray rays, which, unless absorbed, may cause burns and other harmful l0 effects to the operator. In order to absorbthose undesired rays which are propagated radially of the tube, it is customary to position a metallic cylinder which is opaque to X-rays as near as possible to the discharge zone, i. e. closely surrounding the space between the anode and cathode, the cylinder having an opening through which the desired rays may pass. Along the exterior surface of the tube there may also be arranged one or more metallic sleeves, ordinarily concentric and in longitudinal alignment with the inner cylinder and provided with a window which registers with the opening in the inner cylinder. The raysemitted in other directions than the desired one may be absorbed by a cover which extends substantially the entire remaining length of the tube and is held in position preferably by the metal sleeve. The present invention is directed to an improved construction of this covering mem er.

In view of the fact that high voltages are applied between the anode and Vcathode of an X-ray tube, it is evident that the insulation properties of the covering member must meet high requirements under all conditions of temperature and must also be able to withstand concentrated electrical stresses. It has been proposed heretofore to employ for the covering material al phenolic condensation product, but this material has not been found to be suitable in all climates, particularly in tropical climates.

In accordance with our invention, we pro- 4 pose to substitutefor the phenolic condensation material a vitreous or vitrifiable substance such as porcelain which has been found to be a reliable insulator even under r the most adverse conditions. In order to "0 give the porcelain body a sufficient X-ray port for order to -maintain the latter gated cylinders or sleeves manner within a circular slot 13 formed be- GEB'MA-NY, .ASSIGNORS i l .A CORPORATION 0F NEW Y'BCKy ECR x-RAYinfinisv Y 443,588,21116. in Germany 'April 19, 1929. l

absorbing effect, "we propose to apply to the inner or o-uter surfacesv thereof or both, a tenaciously adherent layer of high. atomic materialpreferab-ly in the form ofafglaae or enamel. The invention will be better'understood when reference is made to the following speciication fand the accompanying drawing in which Fig. Vl shows partly in section and partly in diagram an X-ray tube improved in accordance with theprinciples ofj-the invention, while Fig. 2 is an enlarged fragmentary view. In the-drawing, numeral 1 designates the glass envelope of an ISI-ray tube terminatingv in reentrantstems2, 8, which constitute a supthe' anode' 4 and cathode 5 of `usual vand well known design.l The discharge zone between the electrodes is surrounded by a cylinder 6 of a suitable refractory metalwhich is'provided with an opening 7 through which the X-rays emerge. VOn the exterior of the tube andin opposed relation tothe cylinder 6 there is an apertured jacket 8 voflead or equivalent metal for absorbing the radially directed rays which may pass through `the cylinder 6 and the glass wall of the envelope. The j acket is tted within a metalliccasing 9 vofbrassor the like which may serve asa support for the apparatus in the wellunderstood manner. The casingis provided with an opening l() which registers with the'opening in the acket 8 and in the cylinder 6. :In substantially at ground or other desired potential there may be providedA one or more conductors 1l sealed l in the envelope and connecting the .cylinder 6 to the outer metal members. These conductors, if sufficiently stiff, may serve'to support the cylinder. p

,The covering which constitutes the subject of our invention take the form of elon- 12, having sufficient thickness to oHer rigidity of shape and secured at their inner edges in any suitable tween the lead jacket and the brass casing 9,"

as shown. The covering preferably is somewhat larger in diameter than the envelope and is so mounted as to present an annular air space between the members along theinl entire length for ventilation purposes. In` accordance With our invention, th-e cover 12'f is made of porcelain and is coated on the inte-v rior, i. e. the surface adjacent the envelope,V 5 with a substance designed to absorb X-rays.- This substancemay be lead oxide or uranium oxide conveniently applied' as a glaze. The exterior surface of each porcelain cylinder may .also he treated With a lead oxide or uranium. oxide preparation but it is found sufficient and preferable to apply simply a high voltage glaze of" suitable and' Well known material such as is ordinarily employed in the manufacture of high voltage insulators. The interior and exterior glazes or coatings are designated in Fig. 2 by reference characters 14 and l5 respectively.

`'What We claim as new and desire to secure i by Letters Patent of the United States is 1. X-ray apparatus comprisingan evacuated envelope containing anA anode and cathode, a metallic cylinder` Within the envelope surrounding the discharge zone, a metallic cylinder arranged on the exterior of the'envelope and substantially in alignment with the inner cylinder, and a plurality of porcelain sleeves surrounding the envelope and secured to the exterior cylinder, saidsleeves .y being coated with uranium oxide. 2. X-ray apparatus comprising an evacuated envelope containing an anode and a cathode, a metallic cylinder Within the envelope surroundingthe discharge zone, ametallic cylinder arranged on the exterior of the envelope and substantially in alignment with the inner cylinder, and a plurality of porcelain sleeves surrounding the envelope and secured to the exterior cylinder, said sleeves being coated with an X-ray absorbing material. 3. X-ray apparatus comprising an evacuated envelope containing an anode and a cathode, a metallic cylinder Within the envelope surrounding the discharge zone, a metali lic cylinder arranged on the exterior of the envelope and substantially in alignment with the inner cylinder, and a plurality of porcelain sleeves surrounding the envelope and secured to the exterior cylinder, said sleeves i being coated on the interior with an X-ray absorbing material and on the exterior with an insulating material.

In Witness Whereoi', We have hereunto set our hands this 31st day of March, 1930.

i `ALFRED UNGELENK. WALTER HOFMANN. 

